Who is the best hitter in baseball history? This is the classic baseball question. We have tools like fWAR to help us answer these questions today. However, we have a problem: levels of competition have never been uniform. If you search for the best single-season fWARs of all time, you get a lot of players in the live ball era, a few players in the 50s, and Barry Bonds. I don't know about you, but I'm skeptical that the best seasons in baseball history were all played in the 20s or were Barry Bonds:

Season

Name

Raw fWAR

1923

Babe Ruth

15

1921

Babe Ruth

13.9

1920

Babe Ruth

13.3

1927

Babe Ruth

13

2002

Barry Bonds

12.7

2001

Barry Bonds

12.5

1924

Babe Ruth

12.5

1924

Rogers Hornsby

12.5

1927

Lou Gehrig

12.5

1926

Babe Ruth

12

2004

Barry Bonds

11.9

1946

Ted Williams

11.8

1942

Ted Williams

11.6

1956

Mickey Mantle

11.5

1917

Ty Cobb

11.5

1957

Mickey Mantle

11.4

1932

Jimmie Foxx

11.3

1921

Rogers Hornsby

11.2

1967

Carl Yastrzemski

11.1

1929

Rogers Hornsby

11.1

Levels of competition have varied over time. We all know that Babe Ruth didn't have to hit against Satchel Paige, and so was able to face weaker competition than players post-integration. As levels of competition go down, better players are able to stand out more. Athletic training, steroids, spitballs, and international recruitment have varied over the years.

I want to adjust single-season performance for competitiveness. We'll never adjust for things like physical fitness (could Babe Ruth hit at an Aroldis Chapman fastball?), but we can adjust for the general distribution of competitiveness by season. I downloaded all qualified players' fWAR from Fangraphs since 1910. I then calculated the standard deviation of fWAR by season. A higher standard deviation indicates that there is more variation between the average player and the best or worst players on the extremes. Here's what it looks like:

You can see that baseball has grown more competitive over time. The best and worse players stood out less in 2010 than in 1930. You can see a good-sized spike during the steroids era, where players like Barry Bonds presumably benefitted disproportionately from performance enhancing drugs. That bump goes away after drug testing begins.

We can also weight individual seasons by competitiveness and by games played (152 vs 162). Here are the best seasons of all time by weighted fWAR*:

Season

Name

Weighted fWAR

1962

Willie Mays

13.7

1926

Babe Ruth

13.6

1915

Ty Cobb

13.5

2004

Barry Bonds

13.0

1915

Eddie Collins

12.8

1981

Mike Schmidt

12.8

1991

Cal Ripken

12.6

1987

Wade Boggs

12.6

1911

Ty Cobb

12.5

2013

Mike Trout

12.4

1968

Carl Yastrzemski

12.3

1994

Jeff Bagwell

12.3

1913

Eddie Collins

12.2

1914

Benny Kauff

12.2

1919

Babe Ruth

12.2

1947

Ted Williams

12.1

1925

Rogers Hornsby

12.1

2005

Alex Rodriguez

12.1

1985

Rickey Henderson

12.0

2012

Mike Trout

12.0

* Please note that the weights are not directly comparable to normal fWAR.

Not bad! The all-time greats from the 1920s are represented, but so are modern players. Mike Trout already has two of the best single seasons of all time. Alex Rodriguez, Rickey Henderson, Barry Bonds, Cal Ripken and Jeff Bagwell all show up. In fact, the single-season distribution is pretty even overall.

Let's get out of single seasons. Who were the best players of all time by weighted fWAR?

Name

Career Weighted fWAR

Barry Bonds

158.5798

Willie Mays

142.6258

Hank Aaron

130.8907

Tris Speaker

127.6107

Mike Schmidt

126.5993

Ty Cobb

119.9339

Rickey Henderson

113.6577

Alex Rodriguez

113.5173

Babe Ruth

113.2207

Eddie Collins

108.5147

Stan Musial

108.1189

Rogers Hornsby

106.2226

Cal Ripken

104.8136

Joe Morgan

104.0492

Carl Yastrzemski

102.6251

Albert Pujols

101.6452

Frank Robinson

101.1763

Ted Williams

99.46524

Wade Boggs

98.96848

George Brett

98.11801

Players like Lou Gehrig (#10 in unweighted fWAR, out of the top-20 weighted) take a big hit. The 1920s and 1930s were a time of huge outlying performances. Players from the 70s and 80s get a big boost, pushing Henderson, Schmidt, Ripken, and others up. Pujols stands out as a mostly post-steroids era performer.

What do you all think? Does this change the way we should consider players from the Golden Age?